1. Technical Field
The present invention relates to remote control systems for photographic equipment, and in particular to a programmable remote control using microprocessors for both digitally encoded radio signal transmitters and receivers to control a number of functions and pieces of equipment related to lighted photography.
2. Description of the Prior Art
Remote lighting for photography can be a major problem, especially for outdoor shots. Photographing a building or other outdoor scene presents a major problem when the lights must be quite close to the building or scene and the camera must be further away to take in the entire building or scene. Originally, cables were used for remote photography lighting. But now, in most towns it is illegal to string cables across a street. Even when possible to use them, cables present problems: they are heavy and unwieldy and tangle easily and the cables must be hidden from view in the photograph.
A number of remote control devices, sometimes called "radio slaves", use wireless transmission systems to set off remote flash units for photographing distant scenes. Early radio slave units had a very limited range (75 feet maximum), and had no provision for selecting individual remote flashes. More recent units have a slightly better range (100-250 feet). There is a regulatory problem relative to range. The FCC limits the frequency of radio waves averaged over a short time and limits the amount of time of transmission after activating a signal to five seconds of carry-over transmission.
The principle on which radio slave units work does not lend itself to reliable operation; they misfire often. Misfiring presents problems with getting a well-lighted picure. Other difficulties include the recycle time for flashes to be ready for the next flash and a limited number of flashes possible on a battery charge.
More recent radio slave units have selections for different "channels", but they can only set off one of the channels at a time. This means that the photographer has to set the channel of each receiver before going back to the camera. There is no provision for changing flash groupings from the camera. It all has to be done at the flash units.
Prior art units are limited in the functions they perform. Some have a delay feature, but not in a remotely controlled system, and the delay time is the same between flashes. Changeable sequencing and changeable delays are generally not possible from the control unit. And the prior art systems generally serve to set off the flash units only.
Prior art devices that employ light signals from the camera to the flash units are very simple with only a flash activation capability.